I hate to correct a esteemed fellow C&Ver but you need a an english threaded BB and the spindle length will depend on the crankset you wil use, not your BB width.
hen you purchase a new crankset check the specs and see what length spindle you need
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk